Racialized influence of parental education on adolescents’ tobacco and marijuana initiation: Mediating effects of average cortical thickness

Abstract

Various regions of the cerebral cortex, such as the prefrontal cortex, parahippocampal gyrus, insular cortex, temporal cortex, and anterior cingulate cortex, play critical roles in emotion regulation and executive/cognitive control. Given these regions' involvement, it is hypothesized that average cortical thickness might play a role in mediating the socioeconomic gradient observed in substance use behaviors. However, the mechanisms through which average cortical thickness influences the differential impact of socioeconomic factors, such as parental education, on the initiation of tobacco and marijuana use among youths from diverse backgrounds remain unclear. Recent studies indicate that the effects of socioeconomic factors on substance use and brain development are racialized, often showing weaker associations in racialized populations due to social stratification and racism. Our aim was to examine whether average cortical thickness mediates the racialized effects of parental education as a major socioeconomic determinant on the initiation of tobacco and marijuana use among youth. This longitudinal study, spanning 36 months, utilizes data from the Adolescent Brain Cognitive Development (ABCD) study, which included 10,777 pre-adolescents aged 9–10 years. From this, 8263 (76.67%) were White youth and 2514 (23.33%) were Black. Structural equation modeling was employed to assess the mediating role of average cortical thickness in the relationship between parental education (social determinant), race, and the initiation of tobacco and marijuana use, while considering covariates such as sex and age. Socioeconomic factors were predictive of future substance use. However, the association between these socioeconomic factors and substance use was found to be weaker among Black youths compared to White youths. Average cortical thickness partially mediated the influence of the racialized socioeconomic gradient on substance use, indicating both direct and indirect effects. Average cortical thickness acts as a partial mediator in the racialized impact of socioeconomic determinants on the initiation of adolescent substance use, underscoring the intricate relationship between neurodevelopmental and social factors in influencing substance use behaviors. This observation supports a biopsychosocial model that incorporates the effects of racism, aligning with the theory of minorities’ diminished returns.